1. Technical Background
The present invention relates generally to medical devices, and more particularly to a balloon catheter and stent delivery system.
2. Discussion
The present invention involves a balloon catheter for inserting a stent, vascular scaffold, or other medical device to a desired site in a patient for medical treatment The balloon is specially shaped with structural features for cooperating with corresponding stent designs to enhance stent retention.
For purposes of brevity, the following background and description will focus generally on the example of a medical device delivery system, in which the medical device is a stent, and the delivery system is based on a balloon catheter. Of course, other medical devices and other delivery systems that are within the scope of one of the claims below are included in the present invention.
It is desirable to provide a novel combination stent delivery system, along with a unique manufacturing process, having an optimum arrangement of several features. These desirable features include a tendency to retain the stent in position on a deflated balloon, small initial size or profile, bending flexibility, column stiffness or pushability, pull strength, inflation strength (sometimes referred to as “rated burst pressure”), etc.
To provide an optimum arrangement of these features, the present invention recognizes and takes advantage of structural aspects of certain stents, such that the delivery system optimizes stent retention without compromising any of the other performance qualities.
Among the stent structural features that may be utilized by the present invention are an expandable cylindrical mesh or lattice, stents are preferably designed to be flexible during delivery and bend along a vascular path. One design that allows such flexibility is to include a series of main elements for hoop strength, preferably coupled by a series of flexible links to enhance flexibility. The stent should preferably also have an optimum selection of features, including flexibility, small profile, hoop strength when expanded, and resilience, etc.
Accordingly, stent delivery systems of the present invention provide balloons for delivery and expanding the stent, in which the balloon has a deflated shape with a pattern of ridges or bumps. These ridges or bumps tend to increase stent retention during delivery, and preferably cooperate with the pattern of main stent elements and flexible links, to better hold the stent in place on the catheter delivery system.